New UI mock

For work with no reference screenshot to copy. If there is one, use clone-prototype instead. Measurement beats invention every time.

Everything renders on the canvas from mockups/canvases/<slug>/; see prototype-canvas for running it, and its references/layout.md for the folder and layout.json rules.

The plugin ships the template folder and every worked example. sp and refkit are separate — the plugin cannot run an installer of its own. Not on PATH, or sp --version prints something lower than the version this skill shipped with? Run uv tool install "git+https://github.com/ReScienceLab/super-prototyping#subdirectory=tools", adding --force to reinstall over a lower version. Leave a higher version alone, because reinstalling over it would be a downgrade, and the tag may not even exist. sp root then prints where the plugin landed: